Roberto Baldoni Carlo Marchetti Sara Tucci Piergiovanni Asynchronous Active Replication in Three-Tier Distributed Systems. 19-28 2002 conf/prdc/2002 PRDC http://csdl.computer.org/comp/proceedings/prdc/2002/1852/00/18520019abs.htm db/conf/prdc/prdc2002.html#BaldoniMP02